On Fri, Sep 7, 2018 at 5:29 PM Quentin Perret <quentin.per...@arm.com> wrote: > > On Friday 07 Sep 2018 at 10:52:01 (+0200), Rafael J. Wysocki wrote: > > On Thursday, September 6, 2018 4:38:44 PM CEST Quentin Perret wrote: > > > Hi Rafael, > > > > > > On Thursday 06 Sep 2018 at 11:18:55 (+0200), Rafael J. Wysocki wrote: > > > > I'm not a particular fan of notifiers to be honest and you don't need > > > > to add an extra chain just in order to be able to register a callback > > > > from a single user. > > > > > > Right. I agree there are alternatives to using notifiers. I used them > > > because they're existing infrastructure, and because they let me do what > > > I want without too much troubles, which are two important points. > > > > > > > That can be achieved with a single callback > > > > pointer too, but also you could just call a function exported by the > > > > scheduler directly from where in the cpufreq code it needs to be > > > > called. > > > > > > Are you thinking about something comparable to what is done in > > > cpufreq_add_update_util_hook() (kernel/sched/cpufreq.c) for example ? > > > That would probably have the same drawback as my current implementation, > > > that is that the scheduler is notified of _all_ governor changes, not > > > only changes to/from sugov although this is the only thing we care about > > > for EAS. > > > > Well, why don't you implement it as something like "if the governor changes > > from sugov to something else (or the other way around), call this function > > from the scheduler"? > > I just gave it a try and ended up with the diff below. It's basically > the exact same patch with a direct function call instead of a notifier. > (I also tried the sugov_start/stop thing I keep mentioning but it is > more complex, so let's see if the simplest solution could work first). > > What do you think ?
This generally works for me from the cpufreq perspective, but I would add "cpufreq" to the name of the new function, that is call it something like sched_cpufreq_governor_change(). Also do you really need the extra work item? Governor changes are carried out in process context anyway. Thanks, Rafael
